U.S. Pat. No. 6,023,131 discloses a backlight device for a liquid crystal display (LCD), which comprises a high-voltage generating means, whose output can be controlled. The high-voltage generating means comprises an inverter for generating an alternating output voltage. The output of the inverter is connected to first electrodes of three gas discharge lamps, which can emit red, green and blue light, respectively. A second electrode of each lamp is connected to a ground voltage line via a separate first electronic switch. The inverter is connected to a high-voltage source via a second electronic switch. A control circuit is connected to the switches to let them conduct or to block. Only when the second switch is conducting the high voltage is supplied to the inverter, so that it will generate the alternating voltage. The three first switches are controlled such that only one first switch is conducting at a time. There is an off-interval of not conducting of all first switches between on-times of different first switches being conducting. Only the selected one lamp will emit light.
With said prior art backlight device each lamp may emit light during a small part, in particular less than one third, of time only. Therefore, to obtain a certain amount of light during some time on average a relatively high peak current must flow through the lamps. Therefore also, the inverter, the switches and the lamps must be suitable to handle such high peak currents, which causes them to be relatively bulky and expensive.